Field of the invention
[0001] The present invention relates to a method and an apparatus for converting a representation
of a ventilation duct system, in a computer readable form, from a first duct type
to a second duct type, such as circular and rectangular ducts.
Background of the invention
[0002] Ventilation duct systems, hereafter referred to as ventilation systems, could be
constructed with different types of ducts, such as rectangular ducts, circular ducts,
oval ducts etc. A circular duct is a duct which has a circular cross-section in which
the fluidum (air) flows. Accordingly, a rectangular duct has a rectangular cross-section,
etc. Different types of ducts have different properties, and are suitable for different
conditions and situations. However, the choice of duct type is primarily dependent
on which duct type the constructor and/or the engineer constructing the system is
used to work with. Thus, certain duct types are often used, even though they are not
the most appropriate.
[0003] In most cases, the circular ducts are the most suitable. The circular duct elements
are quite similar in different systems, and could be provided as standard products,
which makes them less costly. Less material are also needed to produce circular duct
elements, and less isolation material is needed in case of isolated ducts. Further,
the circular duct elements are easier to assemble and mount, and the assembled systems
are also easier to balance. Still further, the circular duct elements are easier to
seal, and the generation of noise as well as the pressure loss are less. Consequently,
ventilation systems with circular ducts are often to be preferred, compared to systems
with rectangular ducts.
[0004] It is thus a problem, that many constructors are more comfortable using a certain
duct type, e.g. rectangular ducts, in constructing ventilation systems, in spite of
the duct type not being the most suitable.
[0005] Ventilation systems are nowadays usually constructed by means of software for computer
aided design. Conversion between different duct types is possible. However, every
duct element has to be converted manually, making the conversion a difficult and tedious
task. The connection of the converted elements is also a problem. For this reasons
the ventilation systems are usually mounted with the same type of duct elements that
are used in the construction design.
[0006] There is therefore a need for an easier and more efficient method and apparatus for
automatic conversion between ventilation systems with different duct types.
Object of the invention
[0007] It is therefore an object of the present invention to provide a method and an apparatus
for converting a representation of a ventilation system, in a computer readable form,
from a first duct type to a second duct type, such as circular and rectangular ducts,
overcoming the above mentioned problems.
[0008] This object is achieved by means of a method, an apparatus and a computer-readable
medium according to the enclosed claims.
Summary of the invention
[0009] According to the invention, a method for converting a representation of a ventilation
system in a computer readable form from a first duct type to a second duct type, such
as circular and rectangular ducts, comprises the steps of:
obtaining an original representation of a ventilation system comprising several straight
duct elements and connecting duct elements, connecting said straight duct elements,
of the first duct type;
identifying said straight duct elements in the obtained system;
calculating, for each or groups of identified straight duct elements, the equivalent
size of one or several duct elements of the second duct type to provide the same performance
as said duct elements of the first duct type; and
connecting said duct elements of the second duct type with connection duct elements
in accordance with the connection of the corresponding duct elements in the original
ventilation system, whereby a converted representation of the ventilation system is
obtained.
[0010] Hereby, a method, and a corresponding apparatus, is provided for efficient and adequate
conversion of a ventilation system with duct elements of a first duct type to a ventilation
system with duct elements of a second type. This makes it possible for a constructor
used to work with a certain duct type, such as rectangular ducts, to construct systems
with this duct type in a computer readable form, where after the ventilation system
automatically is converted to a more suitable duct type, without changing the performance
and properties of the system. By performance is here meant either that the same fall
of pressure, i.e. pressure drop, is obtained for the same flow, or the same fall of
pressure is obtained for the same flow velocity.
[0011] The conversion according to the invention is preferably made between rectangular
ducts and circular ducts, and by use of the expression:
where D
e is the equivalent diameter of a circular duct corresponding to a rectangular duct
with the width W and the height H, and C is a constant, and preferably about 1.3.
An equivalent expression could be used for the conversion from circular to rectangular
ducts.
[0012] Further, the method preferably comprises the steps of:
defining a maximum height value for the ducts;
comparing the calculated diameter size of the circular ducts equivalent to the rectangular
ducts with the maximum height value; and
in case of the diameter being larger than the maximum height value, dividing the circular
duct in two or more separate circular ducts with a corresponding total cross sectional
area, and each having a diameter less than the maximum height value.
[0013] Hereby, the method automatically adapts to a height restriction defined by the user.
Such restrictions are quite common, and by the inventive method the problem of circular
ducts usually being higher than corresponding rectangular ducts are handled in an
efficient manner.
[0014] Still further, in the case of a duct being divided in several separate ducts, the
connection of the divided duct elements to other straight duct elements in the ventilation
system preferably takes place in order of vicinity, whereby the closest ducts are
connected first. Hereby, the problem of connecting separated ducts is handled efficiently.
[0015] The original representation of the ventilation system is preferably created by means
of a tool for computer aided design of ventilation systems, and the method according
to the invention is further preferably a part of such a tool for computer aided design.
Hereby, the method according to the invention could be incorporated in the normal
working process, and the need for additional working steps and tools are avoided.
[0016] According to a preferred aspect of the invention, the method further comprises the
additional step of searching among available duct elements stored in a database for
elements corresponding to the calculated straight duct elements of the second duct
type or the connection duct elements, and, if such corresponding elements are found,
replacing said element in the ventilation system by the element from the database.
Hereby, the ventilation system could be automatically adapted to available standard
elements or the like, making the implementation of the system easier and more efficient.
[0017] The invention further comprises an apparatus to execute the inventive method, as
well as a corresponding computer-readable medium comprising a program tool with instructions
to perform the steps according to the invention.
Brief description of the drawings
[0018] For exemplifying purposes, the invention will be described in closer detail in the
following with reference to embodiments thereof illustrated in the attached drawings,
wherein:
Fig 1 is a schematic illustration of a ventilation system with rectangular ducts;
Fig 2 is a schematic illustration of the ventilation system in fig 1 after a conversion
to circular ducts; and
Fig 3 is a schematic flow diagram of the conversion method according to the invention.
Description of preferred embodiments
[0019] Referring to fig 3, a method for converting a representation of a ventilation duct
system in a computer readable form from a first duct type to a second duct type according
to a preferred embodiment of the invention should now be described. The invention
is primarily directed to the conversion between rectangular ducts and circular ducts,
and especially from rectangular to circular. However, conversion in the other direction
is also possible by means of the invention. It is also possible to use the invention
for conversion between other duct types, such as between circular and oval.
[0020] The method comprises a first step, S1, in which an original representation of a ventilation
system is obtained, i.e. a ventilation system 1 with duct elements of a first duct
type, such as rectangular. A schematic example of such a ventilation system is shown
in fig 1. The ventilation system 1 comprises several straight duct elements 11-16
and connecting duct elements 17-19, connecting said straight duct elements. The straight
duct components may also be directly connected to each other, in which case the connecting
element could be considered as incorporated in the straight duct elements. The connecting
elements comprise, in regard to this application, duct components such as bends, twin
bends, branches, cross-pieces, tees, reducers, boots, end pieces, couplings, offsets,
etc. In short, all duct components not being straight duct elements are in this application
considered to be connecting elements.
[0021] The representation of the original ventilation system is preferably created in a
design tool for computer aided design of ventilation systems. Such tools are commonly
used by constructors and engineers constructing ventilation system, and e.g. the design
tool CADvent®, provided by the applicant, could be used. However, other ways of obtaining
computer-readable representations of ventilation systems may be used together with
the invention.
[0022] In a second step, S2, the ventilation system is analysed to identify straight duct
elements 11-16. Thereafter, in step S3, the equivalent size of straight duct elements
of a second duct type, such as circular, are calculated. With equivalent is here meant
that the calculated duct element provides the same performance as the duct elements
of the first duct type. Performance is preferably defined as the same fall of pressure
for the same flow, or the same fall of pressure for the same flow velocity.
[0023] In the case where a conversion from rectangular to circular is intended, the calculation
may be made according to:
where D
e is the equivalent diameter of a circular duct corresponding to a rectangular duct
with the width W and the height H, and C is a constant, preferably about 1.3. An analogue
expression may be used in the case of conversion from circular to rectangular, or
in conversion between other duct types.
[0024] Further, the method preferably comprises a step S4, where the calculated height,
i.e. the diameter in the case of circular ducts, is compared to a predefined maximum
height value for the ducts. Such a maximum height value is preferably defined by the
user prior to the conversion. In case of the calculated height being larger than the
maximum height value, the equivalent duct is divided into two or more separate ducts
with a corresponding total cross sectional area, and each having a height less than
the maximum height value, step S5. This step is especially important in conversions
to circular ducts, while a circular duct normally has a diameter exceeding the height
of a corresponding rectangular duct. However, in other conversions, such as from rectangular
to circular, it may be omitted. In this latter case, the method may alternatively
or additionally comprise the steps of identifying straight ducts being arranged in
parallel and adjacent to each other, and during the conversion combining such adjacent
ducts to a single rectangular duct, provided that the height of the rectangular duct
does not exceeds the maximum height value.
[0025] The division of the calculated duct is preferably made to provide ducts having the
same size, i.e. the same diameter. However, ducting having different sizes may be
used, and could be preferred in certain situations. The calculated duct is normally
divided in two. However, it may as well be divided into three or more. Preferably,
a calculation is made prior to the division, to determine the smallest required denominator.
Alternatively a loop is provided, whereby the duct is first divided in two, where
after it is again determined whether the diameters are exceeding the maximum height
value or not. If the diameters are to large, the denominator is increased with one,
and the process is repeated, until a sufficient height is obtained.
[0026] The divisional ducts are preferably positioned in parallel to each other, and distributed
in the width direction of the corresponding rectangular duct, step S6. Hereby, the
total flow centre for the divided ducts, that is the centre of the total flow in all
the ducts, are preferably the same as the flow centre for the original duct. However,
the divided ducts are preferably separated by a distance normally ranging from 0.5-2
times the diameter for the ducts. The distance is preferably defined by the user,
by inputting a value in a dialog box or the like. Further, this separation distance
is preferably possible to define and alter by the user. Other ways of positioning
the ducts may be used as well.
[0027] After the determination of the equivalent straight ducts of the second duct type,
the straight duct elements are connected, by means of connection duct elements, in
accordance with the connection of the corresponding duct elements in the original
ventilation system, step S7. Thus, a first converted representation of the ventilation
system is obtained.
[0028] In the case where a duct has been divided into several separate ducts, the connection
of the divided duct elements to other straight duct elements in the ventilation system
preferably takes place in order of vicinity, whereby the closest ducts are connected
first, step S7. After the connection of the closest adjacently arranged ducts, a determination
is made whether or not there are still pairs of adjacently arranged ducts not being
connected. If this is the case, the connection step, S7, is repeated. Hereby, all
ducts are connected, in order of vicinity, which is the most efficient way of connecting
the ducts. In case two ducts should be connected to only one adjacently arranged duct,
a determination is preferably made whether the flow in the single duct should accommodate
the flow from both the divided ducts. If this is not the case, a decision from the
user is requested.
[0029] In fig 2, there is shown a converted ventilation system 2 corresponding to the system
shown in fig 1. As is clearly seen, some of the straight ducts 13, 14 in the original
system 1 have been replaced by one circular duct 23, 24, while others 11, 12, 15,
16 have been replaced by two separate circular ducts 21', 21'', 22', 22'', 25', 25'',
26', 26''. In the first connection step, the single, i.e. non-divided, ducts 23 and
24 are connected by the element 29. Further, the closest ducts 21'' and 22'' are connected
by 27''; 22'' and 23 by 28; 25' and 22' by 33; and 26' and 22'' by 32. Thereafter,
the other ducts are connected, i.e. 21' and 22' by 27'; 22' and 26'' by 30; and 22''
and 25'' by 31. It should be noted that the duct 22' is not connected to the duct
23. In this case, the reducer 18 could be implemented in a number of ways, and the
method leaves it to the user to decide which way to choose.
[0030] The new, converted ventilation system could thereafter be re-dimensioned automatically.
Hereby, the converted representation of the ventilation system is analysed according
to flow parameters etc defined by the constructor, to adapt the duct elements in order
to optimise the ventilation system, but preferably still with the same maximum height
restriction. The optimisation could be made according to parameters such as size,
performance or total cost.
[0031] The elements of the ventilation system may also, which is preferred, be compared
to predefined components stored in a database. Hereby, elements corresponding to the
calculated duct elements of the second duct type may be found, and if such corresponding
elements are found, they replace the element in the ventilation system, step S9. The
database may contain available standard products, provided by one or several suppliers
of duct components. By the replacement of the calculated duct elements by the available
products, the system becomes much cheaper, and also more easy to assemble and mount,
while the part are easily connectable.
[0032] In cases where no similar or corresponding product could be found, the user is preferably
notified in some way, for example by high-lighting or deleting the element. This provides
the opportunity for the user to choose some other constructional design, where he
could use available standard components.
[0033] The method described above could be implemented by use of an apparatus for converting
a representation of a ventilation system in a computer readable form from a first
duct type to a second duct type. Such an apparatus must comprise the means for execute
the above mentioned steps of the method. Hence, the apparatus must comprise: means
for obtaining the original representation of the ventilation system; means for identifying
the straight duct elements in the obtained system; means for calculating, for each
or groups of identified straight duct elements, the equivalent size of one or several
duct elements of the second duct type to provide the same performance as the duct
elements of the first duct type; means for connecting the duct elements of the second
duct type with connection duct elements in accordance with the connection of the corresponding
duct elements in the original ventilation system and means for storing said converted
representation in a second storage means. The apparatus could be implemented with
an general purpose computer, comprising memory means for obtaining the original ventilation
system and for storing the converted system. The apparatus also preferably comprises
a database comprising available duct elements, or a connection to such a database.
[0034] Hence, the method according to the invention could be implemented as a computer-readable
medium, on which is stored a computer program of instructions for such a general purpose
computer to perform the steps of the method.
[0035] Most preferably, the invention is implemented as a computer-readable medium, on which
is stored a computer program of instructions for a general purpose computer to perform
computer aided design of ventilation systems, and further to perform the steps of
the method. Hereby, the constructor could design the ventilation system with any duct
type, according to his wishes, in a design tool, and thereafter convert the system,
directly in the design tool, to the duct type which is preferred in the present situation.
[0036] The invention has been described above in terms of a preferred embodiment. However,
the scope of the invention should not be limited by this embodiment, and alternative
embodiments of the invention are feasible, as should be appreciated by a person skilled
in the art. For example, the conversion may be carried out between any types of ducts;
the equivalent performance may be defined in a number of ways, depending on the situation;
the computer-readable representation may be created and obtained in a number of ways,
etc. Such embodiments should be considered to be within the scope of the invention,
as it is defined by the appended claims.
1. A method for converting a representation of a ventilation system in a computer readable
form from a first duct type to a second duct type, such as circular and rectangular
ducts, comprising the steps of:
obtaining an original representation of a ventilation system comprising straight duct
elements and connecting duct elements, connecting said straight duct elements, of
the first duct type;
identifying said straight duct elements in the obtained system;
calculating, for each or groups of identified straight duct elements, the equivalent
size of one or several duct elements of the second duct type to provide the same performance
as said duct elements of the first duct type; and
connecting said duct elements of the second duct type with connection duct elements
in accordance with the connection of the corresponding duct elements of the original
ventilation system, whereby a converted representation of the ventilation system is
obtained.
2. A method according to claim 1, wherein, in the calculation of the equivalent size
for the duct elements of the second duct type, the size where the same fall of pressure
is obtained for the same flow is calculated.
3. A method according to claim 2, wherein the conversion is made between rectangular
ducts and circular ducts.
4. A method according to claim 3, wherein the calculation of equivalent size is made
according to:
in the case of conversion from rectangular ducts to circular ducts, where D
e is the equivalent diameter of a circular duct corresponding to a rectangular duct
with the width W and the height H, and C is a constant, and preferably about 1.3;
and whereby the calculation is made in accordance with an analogue expression in the
case of conversion from circular ducts to rectangular ducts.
5. A method according to claim 3, wherein, in the case of conversion from rectangular
ducts to circular ducts, the method comprises the further steps of:
defining a maximum height value for the ducts;
comparing the calculated diameter size of the circular ducts equivalent to the rectangular
ducts with the maximum height value; and
in case of the diameter being larger than the maximum height value, dividing the circular
duct into two or more separate circular ducts with a corresponding total cross sectional
area, and each having a diameter less than the maximum height value.
6. A method according to claim 5, wherein the circular duct is divided into ducts having
the same diameter.
7. A method according to claim 5, wherein the divisional ducts are positioned in parallel
to each other, and preferably distributed in the width direction of the corresponding
rectangular duct, and with the total flow centre being the same as the flow centre
for the original rectangular duct.
8. A method according to claim 5, wherein, in the case of a duct being divided into several
separate ducts, the connection of the divided duct elements to other straight duct
elements in the ventilation system takes place in order of vicinity, whereby the closest
ducts are connected first.
9. A method according to claim 3, wherein, in the case of conversion from circular ducts
to rectangular ducts, the method comprises the further steps of:
identifying straight ducts being arranged in parallel and adjacent to each other;
and
during the conversion combining said adjacent ducts to a single rectangular duct.
10. A method according to claim 1, wherein, in the calculation of the equivalent size
for the duct elements of the second duct type, the size where the same fall of pressure
is obtained for the same flow velocity is calculated.
11. A method according to claim 1, wherein the original representation of the ventilation
system is created by means of a tool for computer aided design of ventilation systems.
12. A method according to claim 1, comprising the additional step of re-dimensioning the
converted representation of the ventilation system, to adapt the duct elements in
order to optimise the ventilation system.
13. A method according to claim 1, comprising the additional step of searching among available
duct elements stored in a database for elements corresponding to the calculated straight
duct elements of the second duct type or the connection duct elements, and, if such
corresponding elements are found, replacing said element in the ventilation system
by the element from the database.
14. A method according to claim 13, wherein the user is warned in cases where, for a certain
element, no corresponding element could be found in the database, for example by high-lighting
or deleting the element.
15. A method according to claim 13, wherein a decision by the user is requested in cases
where, for a certain element, several possible corresponding element could be found
in the database.
16. An apparatus for converting a representation of a ventilation system in a computer
readable form from a first duct type to a second duct type, such as circular and rectangular
ducts, comprising:
means for obtaining an original representation of a ventilation system comprising
duct elements of the first duct type from a first storage means;
means for identifying straight duct elements in the obtained system;
means for calculating, for each or groups of identified straight duct elements, the
equivalent size of one or several duct elements of the second duct type to provide
the same performance as the duct elements of the first duct type;
means for connecting the duct elements of the second duct type with connection duct
elements in accordance with the connection of the corresponding duct elements in the
original ventilation system, whereby a converted representation of the ventilation
system is obtained; and
means for storing said converted representation in a second storage means.
17. An apparatus according to claim 16, wherein said means for calculation of the equivalent
size for the duct elements of the second duct type, is adapted to calculate the site
where the same fall of pressure is obtained for the same flow.
18. An apparatus according to claim 17, wherein, in the case of conversion from rectangular
ducts to circular ducts, the apparatus further comprises:
means for defining a maximum height value for the ducts;
means for comparing the calculated diameter size of the circular ducts equivalent
to the rectangular ducts with the maximum height value; and
means for dividing the circular duct in two or more separate circular ducts with a
corresponding total cross sectional area, and each having a diameter less than the
maximum height value, in cases where the calculated diameter is larger than the maximum
height value.
19. An apparatus according to claim 16, further comprising means for re-dimensioning the
converted representation of the ventilation system, to adapt the duct elements in
order to optimise the ventilation system.
20. An apparatus according to claim 16, further being connected to a database comprising
available duct elements, and comprising means for searching the database for elements
corresponding to the calculated straight duct elements of the second duct type or
the connection duct elements, and, if such corresponding elements are found, for replacing
said element in the ventilation system by the element from the database.
21. A computer-readable medium, on which is stored a computer program of instructions
for a general purpose computer to perform the steps of:
obtaining an original representation of a ventilation system in a computer readable
form comprising several duct elements of a first duct type;
identifying straight duct elements in the obtained system;
calculating, for each or groups of identified straight duct elements, the equivalent
size of one or several duct elements of a second duct type to provide the same performance
as the duct elements of the first duct type; and
connecting the duct elements of the second duct type with connection duct elements
in accordance with the connection of the corresponding duct elements in the original
ventilation system, whereby a converted representation of the ventilation system is
obtained.
22. A computer-readable medium according to claim 21, wherein the program comprises instructions
to perform the step of calculation of the equivalent size for the duct elements of
the second duct type in such a manner that the size where the same fall of pressure
is obtained for the same flow is calculated.
23. A computer-readable medium according to claim 22, wherein the program comprises instructions
to, in case of conversion from rectangular ducts to circular ducts, perform the additional
steps of:
defining a maximum height value for the ducts;
comparing the calculated diameter size of the circular ducts equivalent to the rectangular
ducts with the maximum height value; and
in case of the diameter being larger than the maximum height value, dividing the circular
duct into two or more separate circular ducts with a corresponding total cross sectional
area, and each having a diameter less than the maximum height value.
24. A computer-readable medium according to claim 21, wherein the program further comprises
instructions to perform the step of re-dimensioning the converted representation of
the ventilation system, to adapt the duct elements in order to optimise the ventilation
system.
25. A computer-readable medium according to claim 22, wherein the program comprises instructions
to perform the additional steps of searching among available duct elements stored
in a database for elements corresponding to the calculated straight duct elements
of the second duct type or the connection duct elements, and, if such corresponding
elements are found, replacing said element in the ventilation system by the element
from the database.
26. A computer-readable medium, on which is stored a computer program of instructions
for a general purpose computer to perform computer aided design of ventilation systems,
and further to perform the steps of:
obtaining an original representation of a ventilation system in a computer readable
form comprising several duct elements of a first duct type;
identifying straight duct elements in the obtained system;
calculating, for each or groups of identified straight duct elements, the equivalent
size of one or several duct elements of a second duct type to provide the same performance
as the duct elements of the first duct type; and
connecting the duct elements of the second duct type with connection duct elements
in accordance with the connection of the corresponding duct elements in the original
ventilation system, whereby a converted representation of the ventilation system is
obtained.